The aim of this study was to evaluate and compare the electrical performance and properties of commercially available electroretinography (ERG) electrodes.
A passive ionic model was used to measure impedance, noise, and potential drift in 10 types of ocular surface and skin ERG electrodes.
The impedance for silver-based ocular electrodes are generally lower (range, 65.35-343.3 Ω) with smaller phase angles (range, -6.41° to -33.91°) than gold-based electrodes (impedance ranged from 285.95 Ω to 2.913 kΩ, and phase angle ranged from -59.65° to -70.01°). Silver-based ocular electrodes have less noise (median line noise of 6.48 x 10nV/Hz) than gold-based electrodes (median line noise of 2.26 x 10nV/Hz). Although silver-based electrodes usually achieve a drift rate less than 5 ?V/s within 15 minutes, gold-base ocular electrode cannot achieve a stable potential. The exception is the RETeval strip type of silver electrode, which had an unusual drift at 20 minutes. The noise spectral density showed no change over time indicating that noise was not dependent on the stabilization of the electrode.
From the range of electrodes tested, lower impedance, lower capacitance, and lower noise was observed in silver-based electrodes. Stabilization of an electrode is effective against drift of the electrode potential difference but not the noise.
Application of electrodes with optimized materials improve the quality of clinical electrophysiology signals and efficiency of the recording.
Application of electrodes with optimized materials improve the quality of clinical electrophysiology signals and efficiency of the recording.To assess the influence of limbal metabolic support on corneal edema during scleral-lens (SL) and soft-contact-lens (SCL) wear for healthy lens wearers.
A two-dimensional (2D) model of the cornea and sclera was designed on Comsol Multiphysics 5.4 along with SL and SCL architectures to mimic lens-wear induced hypoxia. The cornea is suffused with oxygen and metabolites from the limbus and aqueous humor. Air oxygen is supplied from and carbon dioxide is expelled to the atmosphere. Lens-oxygen permeability () was adjusted to investigate lens-wear safety against edema in different wear conditions. The 2D concentrations of oxygen, carbon dioxide, bicarbonate, lactate, sodium, chloride, glucose, and pH are quantified. Central-to-peripheral swelling of the cornea is determined by the change in stromal hydration caused by changing metabolite concentrations at the endothelium during hypoxia.
The metabolic model assesses central-to-peripheral corneal swelling with different types of lenses, and oxygen s. Limbal metabolic support reduces edema from the periphery to approximately 1 mm away from the central cornea. Despite thicker lens designs, the peripheral cornea exhibits practically zero swelling due to limbal metabolic support.
The metabolic model accurately predicts central-to-peripheral corneal edema with various contact-lens designs, post-lens tear-film thicknesses, and lens oxygen values. Despite the thicker periphery of most contact-lens designs, lactate and bicarbonate support from the limbus significantly reduces peripheral and mid-peripheral corneal edema, whereas oxygen has a lesser effect.
By utilizing metabolic kinetics, we provide a 2D computational tool to predict oxygenation safety across the entire cornea with various types and designs of contact lenses.
By utilizing metabolic kinetics, we provide a 2D computational tool to predict oxygenation safety across the entire cornea with various types and designs of contact lenses.To investigate feasibility and reliability of 3-dimensional full circumpapillary retinal nerve fiber layer (cpRNFL) analysis in children, with and without glaucoma, without the use of sedation and to recommend a protocol for hand-held optical coherence tomography use.
A cohort of pediatric glaucoma patients and normal children were imaged with hand-held optical coherence tomography to assess the feasibility of obtaining full cpRNFL. Two consecutive scans were acquired in a smaller sample to investigate test-retest repeatability and interassessor reproducibility. The cpRNFL thickness was assessed in four quadrants, at several visual angles from the optic nerve center.
Scanning was attempted in both eyes of 90 children with pediatric glaucoma and 180 controls to investigate feasibility (mean age, 6.98 ± 4.42 years). Scanning was not possible in 68 eyes of glaucoma children mainly owing to nystagmus, unclear optical media, or high refractive errors. https://www.selleckchem.com/products/Streptozotocin.html Where three-dimensional imaging was possible, success at obtaining full cpRNFL was 67% in children with glaucoma and 89% for controls. Seventeen children with pediatric glaucoma and 34 controls contributed to reliability analysis (mean age, 6.3 ± 3.63 years). For repeatability intraclass correlation coefficients across quadrants ranged from 0.63 to 0.82 at 4° and improved to 0.88 to 0.94 at 6°. Intraclass correlation coefficients for reproducibility were also highest at 6° (&gt;0.97 across all quadrants).
We demonstrate that acquisition and measurement of cpRNFL thickness values using 3-dimensional hand-held optical coherence tomography volumes in awake children is both feasible and reliable and is optimal at 6° from optic nerve center.
Our recommended protocol provides guidance on how pediatric optic nerve pathologies are managed by clinicians.
Our recommended protocol provides guidance on how pediatric optic nerve pathologies are managed by clinicians.To study the feasibility of using Cherenkov luminescence imaging (CLI) to evaluate and document ruthenium-106 plaque position during brachytherapy of uveal melanoma.
Ruthenium-106 decays by emitting high-energy beta particles. When the electrons pass through the eye, Cherenkov radiation generates a faint light that can be captured by highly sensitive cameras. Patients undergoing ruthenium-106 plaque brachytherapy for posteriorly located choroidal melanoma were examined by CLI, which was performed in complete darkness with an electron multiplying charged-coupled device camera mounted on a fundus camera modified for long exposures.
Ten patients with tumors ranging from 5.8 to 13.0 mm in largest basal diameter and 2.0 to 4.6 mm in height were included. The plaques had an activity between 0.035 and 0.089 MBq/mmat the time of examination (1-4 days after implantation). CLI revealed the actual plaque position by displaying a circular area of light in the fundus corresponding with the plaque area. The Cherenkov light surrounded the tumor as a halo, which showed some asymmetry when the plaque was slightly displaced.